1. Field of the Invention
The present invention relates to an inkjet recording head which has a nozzle which ejects ink drops, a pressure chamber which communicates with the nozzle and in which ink is filled, a vibrating plate structuring a portion of the pressure chamber, an ink pooling chamber which pools ink to be supplied to the pressure chamber via an ink flow path, and a piezoelectric element which displaces the vibrating plate, and to an inkjet recording device equipped with this inkjet recording head.
2. Description of the Related Art
There have conventionally been known inkjet recording devices in which characters, images or the like are printed onto a recording medium such as a recording sheet or the like which is conveyed-in along a subscanning direction, by ejecting (expelling) ink drops selectively from plural nozzles of an inkjet recording head (hereinafter, simply called “recording head” upon occasion) which moves reciprocatingly in a main scanning direction.
Such an inkjet recording device has piezoelectric system recording heads, thermal system recording heads, or the like. For example, in the case of a piezoelectric system recording head, as shown in FIGS. 32 and 33, a piezoelectric element (an actuator which converts electrical energy into mechanical energy) 206 is provided at a pressure chamber 204 to which ink 200 is supplied from an ink tank via an ink pooling chamber 202. The piezoelectric element 206 flexurally deforms in a concave form so as to reduce the volume of the pressure chamber 204, thereby applying pressure to the ink 200 therein and ejecting the ink 200 as an ink drop 200A from a nozzle 208 which communicates with the pressure chamber 204.
In recent years, the ability to achieve high resolution printing while keeping the inkjet recording head low-cost and compact has come to be demanded of inkjet recording heads structured in this way. In order to address such demands, nozzles must be disposed at a high density. However, in current recording heads, as illustrated, because the ink pooling chamber 202 is provided next to the nozzles 208 (between the nozzle 208 and the nozzle 208), there are limits to placing the nozzles 208 at a high density.
Further, the inkjet recording head is provided with driving ICs for applying voltage to predetermined piezoelectric elements. Conventionally, as shown in FIGS. 34A and 34B, the driving ICs are mounted at an FPC (flexible printed circuit board) 210. Namely, connection is carried out by joining bumps 212, which are formed on the FPC 210, to the metal electrode surfaces of the piezoelectric elements 206 which are the top surfaces thereof. Because the driving ICs (not shown) are mounted at the FPC 210, the piezoelectric elements 206 and the driving ICs are electrically connected at this stage.
There is a method of connecting electrode terminals, which are provided at the external surface of the recording head, and electrode terminals, which are on the mounting substrate at which the driving ICs are mounted, by a wire bonding method (see, for example, Japanese Patent Application Laid-Open (JP-A) No. 2-301445). Further, there is a method in which, after joining and connecting the driving ICs to the electrode terminals provided at the external surface of the recording head, connection is carried out by joining an FPC to the electrode terminals of the lead wires provided at the recording head (see, for example, JP-A No. 9-323414).
In either case, wires having a fine pitch (e.g., a pitch of 10 μm or less) cannot be formed. Therefore, if the nozzle density becomes high, problems arise such as the sizes of the mounting substrate and the FPC become large, there are impediments to making the inkjet recording head compact, and costs increase. In addition, if the nozzle density becomes high, there is the problem that wires having desired resistance values cannot be led-around. Namely, there are limits to increase the density of the nozzles, which limits are due to the limitations on the density of the wires.